The Clinical Scholars Biomedical Research Training Program at Memorial Sloan-Kettering Cancer Center (MSKCC) provides a mentored laboratory training experience in cancer research for a group of outstanding MD's or MD/PhD's. This training will prepare highly qualified physician-scientists for a career at the interface of cancer biology and clinical research. Six positions are requested. The fellows are trained by principal investigators, drawn from the professional staff of Memorial Sloan-Kettering Cancer Center who are laboratory investigators. A structured and cohesive two-year training program has been designed to provide outstanding mentorship in guided laboratory research, didactic course work in modern biology and bioinformatics and career development skills. Trainees have access to all resources of the Memorial Sloan-Kettering Cancer Center. The areas of principal emphasis for research include: 1) Signals and pathways involved in control of cell proliferation;2) Regulatory pathways involved in developmental biology and cell differentiation;3) Cell-cell interactions, adhesion and protein targeting;4) Tumor immunology, immunotherapy and transplantation biology;5) Human cancer biology, mouse models of cancer, genetics and molecular pathology;and 6) Drug development and therapeutics. Physicians-scientists receiving training from this program will be poised to more readily translate the recent revolutionary discoveries of biomedical, cancer-related research into patient care.